The parasiticide ivermectin has been administered to domestic livestock since 1981 to control internal and external parasites, including insects; some of the ivermectin is excreted unchanged in faeces. Concerns over the effects of ivermectin on dung-utilising insect populations and the potential for consequent persistence of dung on pastures have been raised. This paper presents the results of a study over two grazing seasons of the rate of decomposition of cattle dung pats exposed to normal environmental influences. The cattle had been treated at therapeutic levels with either an injectable or a sustained release bolus formulation of ivermectin. It was concluded that the rate of decomposition of the dung pats, the extent of their avoidance by the cows, the organic matter content of the soil and the populations of earthworms in the pastures were not affected by the use of ivermectin.

The existing standardised test systems for assessing the toxicity of crop protection products to the non‐target arthropods Typhlodromus pyri (Acari: Phytoseiidae) and Aphidius rhopalosiphi (Hymenoptera: Aphidiidae) are limit tests designed to compare a single‐use rate of the product with a water control. The suitability of these test systems for generating dose‐response data as required for refined ecotoxicological risk assessment was evaluated. Data on dose‐response toxicity of crop protection products to T. pyri and A. rhopalosiphi were generated under worst‐case laboratory and to T. pyri under extended laboratory conditions and analysed using the standard Probit method, a logistic regression, a generalised Probit analysis, and the moving average‐angle method in order to calculate the LR50‐values (application rate killing 50 % of the exposed organisms). The fit of the models, the precision of the resulting LR50 values, and the required minimum number of replicates were compared. In 85 % of the studies, at least one of the statistical methods led to satisfactory results. The moving average‐angle method was the most widely applicable method. The results show that the existing guidelines can be used to perform dose‐response tests. Implications for risk assessment are discussed.

This guideline describes a standardised form of extended laboratory test for evaluating the effects of plant protection products on the parasitic wasp, Aphidius rhopalosiphi (De Stefani-Perez) (Hymenoptera, Braconidae), both in terms of acute treatment effects (i.e. mortality over a 48 h exposure period) and sub-lethal treatment effects (i.e. changes in the reproductive capacity of surviving wasps). The test method involves the treatment of a 3-dimensional test substrate (barley seedlings), over which the test insects (laboratory-bred female wasps, less than 48-hold) are confined for 48 h. Surviving wasps are then individually confined over untreated aphid-infested plants for 24 h and the numbers of parasitised aphids in which wasp pupae subsequently develop are recorded. Acute mortality after 48 h and the mean number of 'mummies' (the pupal stage of the wasps) produced per female are used as assessment endpoints for the test.

No abstract

No abstract